1. Field of the Invention
The invention relates to an electronically commutatable motor.
2. Description of the Prior Art
German patent application 100 644 86.4 contains a detailed discussion of an electronic control of a motor of the type with which this invention is concerned, and the explanations contained therein also relate to the electronically commutatable motor proposed here.
The method described in German patent application 100 644 86.4 concentrates in particular on determining the rotor position of the electric motor, not on particularly advantageous embodiments made possible through its design and type of control. These are the subject of the current application, which relates to the use of this type of motor as a drive motor for safety-critical auxiliary drive units in motor vehicles, in particular to its use as a drive motor of an electrical power-assisted steering unit. The design and control of a motor of this kind fulfill the requirements of the safety concept of the drive unit, which provides that in the event of a malfunction, it is possible to influence the motor so that it does not exert any moment, in particular no braking moment, that compromises the safety of the motor vehicle when the steering mechanism of a motor vehicle is actuated. The reason for the use of the electronically commutatable motor in the current invention, therefore, is not even primarily the frictionless, low-maintenance design thanks to the lack of brushes, but—in addition to the low degree of moment waviness that can be influenced by the control—in particular the possibility for control in the event of a malfunction in a component of the motor control or in the motor itself, particularly if there is a short-circuit in the winding, where short-circuit currents are produced that are on the same order of magnitude as the rated currents and exert dangerous moments on the drive unit. In particular, malfunctions of this kind can lead to the fact that, for example with an electrical power-assisted steering unit, not only does the steering assist fail, but an opposing moment is also produced, which makes it practically impossible to steer the vehicle.